1. Field of the Invention
The present invention relates to a numerical control device and more particularly to a numerical control device capable of recording the history of operations, which are performed from the occurrence of an alarm to the release of the alarm, in the numerical control device as alarm corrective measure operation history information, and displaying the recorded alarm corrective measure operation history information together with an alarm message on a screen when the same alarm is raised next time.
2. Description of the Related-Art
In a numerical control device, if an alarm is raised due to the occurrence of a problem with a machine or the like under control, the alarm is released according to the procedure illustrated in FIG. 5. If an alarm is raised while an operator is performing a task by operating the numerical control device and an alarm message is shown on a display unit of the numerical control device, then the operator sees the message and investigates the cause by referring to the displayed message so as to identify the cause that has triggered the alarm.
Thereafter, the operator operates an MDI unit, a control panel or the like of the numerical control device thereby to correct the data that causes the occurrence of the alarm, and resets the numerical control device or starts the automatic operation. The numerical control device carries out the resetting thereof or the automatic operation in response to the operation by the operator. The operator continues the task if the alarm is released, or repeats the investigation into the cause of the alarm if the alarm is not released.
In the procedure for releasing the alarm according to the prior art illustrated in FIG. 5, an operator refers to an alarm message displayed on a screen to investigate the cause of the alarm. In many cases, however, the alarm messages displayed on the screen of the numerical control device simply state the events that have happened. This has been posing a problem that the displayed alarm messages do not provide an operator with sufficient information required to investigate the causes of the alarms.
Further, when an operator investigates the cause that has triggered an alarm, the time required for the operator to identify the cause for the alarm or the time required for the operator to carry out an operation to release the alarm considerably varies, depending on the amount of knowledge or experience of the operator. This has been posing a problem that differences among operators lead to different operating times of a machine under control.
To cope with the foregoing problems, the art described in Japanese Patent Application Laid-Open No. 2012-113586 intends to solve the problems by recording, as a history, the operations of changing the operation monitoring screen carried out by operators when alarms are raised, and when a new alarm is raised, the operation carried out in the past that is related to the alarm is extracted from the history and the details of the operation are displayed.
However, according to the art described in Japanese Patent Application Laid-Open No. 2012-113586, the information recorded as the history includes only the screen changing operations, so that it is thought to be difficult to obtain the information on the specific operation or procedure for releasing an alarm. This does not satisfactorily solve the problems described above.